The invention generally relates to a rail vehicle and method for installation and removal of railroad crossties or sleepers. A tie exchanging apparatus extracts and loads old ties, and unloads and installs new ties. The apparatus comprises at least one tie distribution car, a tie collection car and a storage car, each having interconnected guide rails bridging between cars, permitting a tie loading vehicle and a tie transport vehicle to move from car to car. The tie loading vehicle transfers ties from the storage cars to a storage basket which is structured to fit removably in a gondola car for temporarily holding a number of ties. The transport vehicle engages the basket and transfers it over the guide rails to an active location along on the tie exchanging vehicle where the ties are unloaded and distributed or collected for storage.
Railways comprise a bed of ballast material, such as size four stones, in which ties are embedded and support rails laid thereupon at a specific gauge width. The rails are set on tie plates and fastened to the ties by anchors and spikes, clips or the like. In the U.S., rail ties are usually made of wood or a similar material that absorbs shock as trains pass, although concrete ties are also used. As trains pass over, the rails are subjected to compressive and shearing forces that tend to loosen the spikes and anchors from the ties over time. Wooden ties also weather, becoming dry and brittle. Eventually, ties fatigue and fracture under the stresses imposed, and accordingly it is necessary to replace the ties regularly. All the ties along a section of the railway may be changed, or only selected ties.
Replacing rail ties is a formidable task. The rails are disengaged from the ties to be replaced by removing their spikes. For full tie replacement, the tracks are lifted and rethreaded onto the new ties. In any event, the ties are pulled laterally from under the track. A new tie is inserted, and tie plates, spikes and anchors are installed to couple the rail to the tie. The ballast is re-arranged, if necessary, by tamping and vibratory stabilization, often accompanied by realignment and elevational adjustments to the track.
Railway ties are usually replaced using a multi-car apparatus that replaces ties on a section of track as it travels over that section. Specialized rail cars have tie removal machinery and means to remove, unload and install ties. Advantageously, worn ties that are removed are exchanged with newly installed ties, rather then being left along the track for later collection. In addition to storage space for the ties, the apparatus can include various transport conveyors, tie removal devices and mobile cranes for manipulating the ties.
An example of a rail carried system is disclosed in U.S. Pat. No. 5,467,717 -Theurer, wherein a multi-car work train has tie storage cars, tie pulling and insertion devices and movable cranes. Two mobile boom cranes that engage individual ties are longitudinally movable on flanged wheels along guide rail sections atop the front and rear cars, and over gondola a cars bridged by a guide rail track. A load-straddling gantry crane is movable on guide rail sections that bridge between the tie storage cars for moving groups of stacked ties. The cranes are used for manipulating old and new ties in conjunction with tie pullers and inserters, conveyors and storage areas for the old and new ties.
The front and rear cars carry the cranes for assisting in the removal of old ties and the placement of new ties. For example, the front car crane can reach down to the track area for grasping ties left by the tie puller. The gantry crane is used for transporting old ties to a storage car and new ties to the rear of the train where the rear car crane lays the ties on the tracks for insertion underneath the rails.
Although Theurer discloses an integrated tie replacement system, it would be advantageous to improve the efficiency of storage and transportation of the ties. Theurtr utilizes open flat cars with upright supports which abut longitudinally against stacks of laterally extending ties. This is a compact arrangement for new ties, but old ties often are broken or splintered and do not stack in an organized manner. Old ties need a container or the like that is sufficiently closed to contain splintered ties and shards, but which nevertheless is readily accessible and can be fully loaded.
The span of the Theurer gantry crane that is movable atop flatbed cars for transporting ties limits the number of ties that can be engaged. A gantry crane also requires a high vertical clearance that can pose a problem during tie exchanging operations in vertically confined spaces such as tunnels.
It would be advantageous to provide a tie exchanging train and a method of exchanging ties which optimizes the efficiency of storage and transportation of rail ties along the length of the train.